Some Considerations on Stability of Electrical Resistance of the TiO2/SnO2Ceramic Moisture Sensor

Studies on the stability of the electrical resistance of the ceramic moisture sensor related to the water adsorption properties of the ceramics by using a solid disk device made of Ti02/SnO2ceramics are reported. The relationships between the resistance increase of the device due to chemisorption of water to form hydroxyl groups and the microstructure of the ceramics by analyzing the´data of scanning electron micrograph (SEM), powder X-ray diffraction, and by the resistance variation tests of the device in vacuum with water injection were studied. Also the life-tests of the device over 3000 h were performed under the excitation of AC 100 Hz in the atmosphere. Finally the possibility of the practical use of the device without heating the moisture-sensitive element by introducing the simplified equivalent circuit of the ceramic moisture sensor was discussed.